1. Field of the Invention
The present invention relates to a method of monitoring the performance of a working tool and more particularly, to a method of monitoring the performance of a working tool by sensing the force or a function of the force applied to the tool and determining a mathematically smoothed function of force such as cumulative percentage deviation for each sensed force reading and utilizing the cumulative percentage deviation data points to determine whether the tool is functioning properly and to control the feed rate between the tool and workpiece to insure that the tool is performing properly.
Methods of monitoring tool wear are well-known in the prior art. Such known methods include monitoring torque, power, current, and pressure to determine whether a tool is functioning properly. The known methods of tool monitoring do not provide the degree of reliability which is necessary in an industrial environment. The present invention attempts to overcome the prior art disadvantages by providing a new and improved method of monitoring the performance of a cutting tool by utilizing an established trend in cumulative percentage deviation (CPD) data points. Prior art such as the Forath U.S. Pat. No. 3,545,310 discloses a tool wear sensor which among other things utilizes the torque gradient to determine tool wear. Watanabe U.S. Pat. No. 3,834,615 also discloses measuring various forces and utilizing a torque gradient to measure tool wear. Tsukava U.S. Pat. No. 4,090,403 and Frecka U.S. Pat. No. 4,237,408 discloses other tool monitoring systems which sense torque and/or power. Other known methods of monitoring tools include monitoring the cumulative percentage deviation of the torque associated with a cutting tool and establishing a high limit against which the cumulative percentage deviation is compared and the machine is shut down if the high limit is reached.